Dear Author,

We read your paper entitled `Clinical factors associated with malignancy and HIV status in patients with ocular surface squamous neoplasia at Kililmanjaro Christian Medical Centre, Tanzania' with much interest. It was an interesting insight into the characteristics of OSSN patients in sub-saharan Africa. However, we had some queries and we hope you can share your thoughts on them.

Firstly, we note that patients were selected based on external appearance of lesions and we feel that this creates a selection bias as patients with clinically less prominent lesions are less likely to be recruited into the study. Your groupings of malignant lesions have included mild to moderate dysplasia, many of which may be clinically less prominent than more dysplastic lesions. This creates a bias where patients selected are more likely to be of a higher dysplastic grade. However, we do agree that selecting a large random group of patients from the general population and testing them histologically may not be feasible.

Our second point is that the p value for independent association with HIV status in the text (p = 0.035) is different from that in the table (p = 0.01) Thirdly, we note that you have concluded that HIV positive patients tend to have a higher malignancy grade based on a regression model. However, we were wondering if there was any explanation for the fact that CD4 counts did not show a similar association. Furthermore, you concluded that positive HIV status was associated with longer lesion duration, larger lesion size, leukoplakia and the presence of feeder vessels. However, this raises a few questions. Firstly, most would agree that a lesion of longer duration is more likely to be of a larger size with corresponding feeder vessels and show leukoplakic changes than one present for a shorter duration. If it possible then that, HIV status was associated with the above risk factors(large size, feeder vessels, leukoplakia) as HIV patients themselves were more likely to have a lesion present for a longer duration of time? Also, it is mentioned that women comprised of 69% of HIV patients. We were wondering if in your experience, women in sub-Saharan Africa may have lesser access to medical care which could have contributed to the longer duration of lesions seen in HIV patients.

Lastly, it is stated that HIV patients are more likely to suffer a recurrence. However, if HIV patients are more likely to have a larger lesion for a longer duration, would this contribute to a higher recurrence rate? Also, if HIV status is a postulated risk factor for the development of dysplasia, it is highly conceivable that there are multiple dysplastic foci. It is then possible that a `recurrent lesion' is in fact the progression of a dysplastic lesion of another focus? As such, were all the recurrences in the same spot of excision?

Thank you for your time and we hope to hear your thoughts on the above queries!

References:

1. Clinical factors associated with malignancy and HIV status in patients with ocular surface squamous neoplasia at Kilimanjaro Christian Medical Centre, Tanzania. Makupa II, Swai B, Makupa WU, White VA, Lewallen S. Br J Ophthalmol. 2012 Apr;96(4):482-4. Epub 2011 Nov PMID: 22075543

Conflict of Interest:

None declared